From 56b39c463918fb0eb9cb15018beb32b358c00e18 Mon Sep 17 00:00:00 2001
From: Jeff Moyer <jmoyer@redhat.com>
Date: Thu, 19 Oct 2006 23:28:13 -0700
Subject: [PATCH] --- yaml --- r: 39949 b: refs/heads/master c:
 fb5527e68d495650a7658fec9a7246bf922db212 h: refs/heads/master i:   39947:
 66b1895d355901192c17b0ebd1aca55dc4d8d592 v: v3

---
 [refs]             |  2 +-
 trunk/mm/filemap.c | 51 ++++++++++++++++++++++++++++++++++++++++------
 2 files changed, 46 insertions(+), 7 deletions(-)

diff --git a/[refs] b/[refs]
index 10725f04a34b..8b1195de5223 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: e8e82b76e0312827f5ae04b573a05b02854a447e
+refs/heads/master: fb5527e68d495650a7658fec9a7246bf922db212
diff --git a/trunk/mm/filemap.c b/trunk/mm/filemap.c
index 3464b681f844..57faa8d12099 100644
--- a/trunk/mm/filemap.c
+++ b/trunk/mm/filemap.c
@@ -2222,7 +2222,7 @@ __generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
 				unsigned long nr_segs, loff_t *ppos)
 {
 	struct file *file = iocb->ki_filp;
-	const struct address_space * mapping = file->f_mapping;
+	struct address_space * mapping = file->f_mapping;
 	size_t ocount;		/* original count */
 	size_t count;		/* after file limit checks */
 	struct inode 	*inode = mapping->host;
@@ -2275,8 +2275,11 @@ __generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
 
 	/* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
 	if (unlikely(file->f_flags & O_DIRECT)) {
-		written = generic_file_direct_write(iocb, iov,
-				&nr_segs, pos, ppos, count, ocount);
+		loff_t endbyte;
+		ssize_t written_buffered;
+
+		written = generic_file_direct_write(iocb, iov, &nr_segs, pos,
+							ppos, count, ocount);
 		if (written < 0 || written == count)
 			goto out;
 		/*
@@ -2285,10 +2288,46 @@ __generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
 		 */
 		pos += written;
 		count -= written;
-	}
+		written_buffered = generic_file_buffered_write(iocb, iov,
+						nr_segs, pos, ppos, count,
+						written);
+		/*
+		 * If generic_file_buffered_write() retuned a synchronous error
+		 * then we want to return the number of bytes which were
+		 * direct-written, or the error code if that was zero.  Note
+		 * that this differs from normal direct-io semantics, which
+		 * will return -EFOO even if some bytes were written.
+		 */
+		if (written_buffered < 0) {
+			err = written_buffered;
+			goto out;
+		}
 
-	written = generic_file_buffered_write(iocb, iov, nr_segs,
-			pos, ppos, count, written);
+		/*
+		 * We need to ensure that the page cache pages are written to
+		 * disk and invalidated to preserve the expected O_DIRECT
+		 * semantics.
+		 */
+		endbyte = pos + written_buffered - written - 1;
+		err = do_sync_file_range(file, pos, endbyte,
+					 SYNC_FILE_RANGE_WAIT_BEFORE|
+					 SYNC_FILE_RANGE_WRITE|
+					 SYNC_FILE_RANGE_WAIT_AFTER);
+		if (err == 0) {
+			written = written_buffered;
+			invalidate_mapping_pages(mapping,
+						 pos >> PAGE_CACHE_SHIFT,
+						 endbyte >> PAGE_CACHE_SHIFT);
+		} else {
+			/*
+			 * We don't know how much we wrote, so just return
+			 * the number of bytes which were direct-written
+			 */
+		}
+	} else {
+		written = generic_file_buffered_write(iocb, iov, nr_segs,
+				pos, ppos, count, written);
+	}
 out:
 	current->backing_dev_info = NULL;
 	return written ? written : err;